Re: [PATCH] [RFC] notify userspace about time changes

From: john stultz
Date: Wed Aug 04 2010 - 11:59:16 EST


On Wed, 2010-08-04 at 15:48 +0300, Alexander Shishkin wrote:
> Certain userspace applications (like "clock" desktop applets or ntpd) might
> want to be notified when some other application changes the system time. It
> might also be important for an application to be able to distinguish between
> its own and somebody else's time changes.

So NTP doesn't actually care, as it will notice the STA_UNSYNC flag is
set the next time it checks adjtimex.

The clock apps example seems reasonable, but maybe isn't the most
compelling argument for adding a new kernel api.

Is there a actual use case that you need this for? I don't really have
an issue with the code I just really want to make sure the feature would
be useful enough to justify the API and code maintenance going forward.

Doing some of my own googling, I see Apple added such a notification
method, which suggests there are apps that want this.
http://stackoverflow.com/questions/690326/how-can-i-get-notified-of-a-system-time-change-in-my-cocoa-application

But it doesn't give any specific examples either.

thanks
-john


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